The invention pertains to the use, of a very low cost drainage system, also for providing subsurface irrigation and means to aerate the land for growing crops. Also the drainage system provides a very low cost heat transfer system to use the ground as a source of cooling or warming for water used in air conditioning, house heating and industrial uses like power plants.
Previous drainage systems for farm land have been expensive and enormous areas of farm land have not been provided with the optimum amount of drainage for crop production. Subsurface irrigation systems provide irrigation without large evaporation losses of expensive and short irrigation water. But in the past subsurface irrigation systems have been too expensive to provide.
The use of the ground to provide cooling for water used as condenser water for power plants or for water used for air conditioning involves pipes buried below the ground with an enormous problem of transferring heat between the pipe and the ground. By using thin-walled plastic tubing an enormous area for heat transfer can be provided at very low cost, but of equal importance is a means to maintain the conductivity of heat through the soil at a maximum level by a means to guarantee the soil will always be quite moist. Normally the combination of plants growing on the surface of the ground and the heat being released to the ground by the cooling of the water in the pipes will during summer drouths frequently dry out the soil around the pipes and reduce the rate of heat transfer from the pipes as much as two-thirds or more. While an irrigation of the ground with water is an obvious solution usually a reason that one would use buried pipes for cooling is that one is short of cheap irrigation water to start with. So the very efficient use of the irrigation water the invention provides, in which evaporation losses can be greatly reduced, is a great advantage.
There is virtually no prior art for the invention unless one views the art for compacting the soil for foundations of buildings. Casagrande in U.S. Pat. No. 3,386,251 expands flexible membranes to force water out of soils for foundations so the soil is strengthened and stabilized.